1. Technical Field
The invention relates to an in-line valve adapted to be installed into an existing fluid line without first stopping the flow of fluid through the line and to a method of accomplishing the same. More particularly, the present invention relates to an in-line valve which will remove two circular portions from a fluid conduit to allow a valve stem to travel therethrough, expand, and block all flow through the conduit.
2. Background Information
Due to budget constraints or to the particular construction and layout of a fluid system within a commercial or industrial building or complex, shutoff valves are not always placed in each line that branches from a main fluid line. Inasmuch as it is not practical for the entire flow system to be shut down in order to effect repairs on a single system branch, or to shut down the entire system to effect repairs on the end of a fluid conduit, it becomes necessary to isolate only that portion to be repaired. In this manner, only that portion of the building serviced by the conduit under repair will be inconvenienced rather than the entire structure. To accomplish this isolation, a valve was required that could be installed into an existing fluid line without first shutting off the flow of fluid through the line so that the flow of fluid is only stopped downstream of the valve without any interruption of the fluid flow upstream of the installed valve.
Existing in-line valves have been developed which perform generally satisfactorily in that they can be mounted in an existing fluid line and provide a shutoff therefor without interrupting any flow upstream of the valve. However, these known valves do present some problems which detract from the ease and feasibility of installation. Specifically, the closest known prior art valve to that of the present invention includes a single rigid solid shaft with a cutter being loosely mounted at the end thereof, in combination with an expandable elastomeric sealing sleeve mounted on the shaft adjacent the cutter. The loose mounting of the cutter on the end of the shaft was necessary to enable the cutter to push against the flexible sleeve and expand it outwardly to preclude fluid flow through the conduit after the cutter cut through the conduit. However, the looseness of the cutter would allow the cutter to sway from its axial orientation with respect to its mounting shaft as it cut through the conduit, and begin cutting in a direction that differed from the axis of the shaft. As such, the aperture that is cut through the conduit may be irregularly shaped creating an area where leakage could occur. Also, a more drastic result occasionally occurred in that the cutter would actually cut through the side of the valve body creating weakness, and possible failure within the valve body itself.
Secondly, as the cutter cut through the conduit, a constant pressure would remain on the expandable sleeve seal thereby weakening the seal, as well as making the cutting process itself more difficult. Furthermore, the teeth of the cutter of such prior art valves would bend inward around the removed metal parts of the conduit after contacting a hardened steel ring, thereby making the removal of the removed metal discs difficult or impossible. The teeth curling is a result of the two following design problems. First, the end-play or loose mounting of the cutter on the shaft causes the teeth to constantly score the inner wall of the valve body forcing the teeth inward. Secondly, the valve is turned until a hardened steel split ring, recessed within the valve body wall, is struck by the cutter teeth. When the teeth contact this harder material, they turn inward thereby trapping the removed metal discs. This trapped removed metal presents a blockage problem especially when the valve is used to create a T-joint, rather than simply to add a shutoff valve in an existing conduit. In either situation, the removed metal portions or discs must be removed from the valve so that when the valve is opened to allow fluid to travel back through the conduit, the removed metal does not work loose and become trapped thereby blocking the conduit.
Thus, despite the existence of the above discussed prior art valve, the need exists for an in-line valve in which the cutter is firmly mounted on the end of the shaft as it cuts through an existing conduit without effecting the subsequent outward expansion of a seal mounted on the shaft for temporarily blocking the flow of fluid through the valve.